Regulating transformer



Jan. 9, 1940- M. SCHWAIGER REGULATING TRANSFORMER Filed March 5, 1938 2 Sheets-Sheet l SSES:

WITNE INVENTOR Max 5 W496):

Jan. 9, 1940 1 SCHWMGEB 2,186,211

REGULATING TRANSFORMER Fi led March 5, .1958 2 Sheets-Sheet 2 WITNESSES:

INVENTOR Q Z WKW Max 5 Wd/jif Patented Jan. 9, 1 940 UNITED STATES PATENT OFFICE to Westinghouse Electric & Manufacturing Company, East Pittsburgh, Pa., a corporation of Pennsylvania Application March 5, 1938, Serial No. 194,117 In Germany April 7, 1937 6 Claims.

provided for varying the voltage ratio betweenthe primary and secondary circuits.-

acter to provide a fixed or unregulated winding portion and a variable or regulated winding portion, the two portions together forming an autotransformer in which the regulated portion boosts or bucks the voltage of the unregulated portion to control the secondary or output voltage in steps above and below the voltage of the supply or primary voltage. The fixed winding portion of a transformer may remain continuously energized from the primary circuit and the regulated winding portion may be included in the secondary circuit to provide a controlled increase or decrease in the voltage applied to that circuit.

Should a short circuit occur on the secondary J1) circuitof. the transformer when the regulated winding portion is connected in voltage opposition to the unregulated portion, the short circuit current may be very large due to the lowered effective reactance of the transformer.

29 To overcome this undesirable condition, a portion only of the unregulatedwinding portion may be used in series with selected parts of the regulated winding portion which is provided with taps to control the voltage in steps over a given 39 range in voltage. After. the tap selecting switch has operated throughout one range of voltage steps, a difierent part of.the unregulated porton of the transformer winding may be connected in series with the regulated portion to provide an extended or diflerent range of regulated voltage steps. During the changeover from one range of voltage steps to another range of voltage steps, certain switching operations are necessary which render this arrangement undesirable.

so It is an object of my invention to provide a tap chang ng transformer in which the above enu merated disadvantages are overcome.

Other objects and advantages of my invention will be apparent from the following description 45 of certain preferred embodiments thereof, reference being had to the accompanying drawings, in which:

Figures 1, 2, 3 and 4 illustrate prior arrangements of apparatus and circuits providing regu- 54) lating transformers having a plurality of tap connections; and "Figs. 5 to 12, inclusive, illustrate apparatus and circuits arranged in accordance with several embodiments of the invention.

Referring to the drawings, Figs. 1 and 2 illusit is customary in transformers of this chartrate one known arrangement of providing variable voltage transformers in which a fixed or unregulated winding portion 1 and a variable or regulated winding portion 2 are provided, and connected to receive energy from a primary or supply circuit represented by conductors 3 and 4, and to deliver energy to a secondary or load circuit represented by conductors 3 and 5. The winding portion 1 is connected between conductors 3 and l as illustrated to be continuously energized in accordance with the voltage of the pri mary circuit. The winding portion 2 is provided I with a series of. taps connected to a row of contacts indicated generally at 6, and including the SeVela]. contacts l, c, a, It, ll, 92 and as which cooperate with a movable tap selector contact i l to form a tap changingswitch. The contact It is connected through a movable switch contact member and contact it to the secondary circuit conductor 5 when in the position illustrated in Fig. l. and through contact members l5 and ll to the circuit conductor *2 when in the position illustrated in Fig. 2. A- switch contact member it is provided for connecting the upper .end of the winding portion 2 through contact rnember it, to conductor 4 when in the position illustrated in Fig. 1 and through contact member 28 to conductor 5 when in the position illustrated in Fig. 2.

When the switch members l5 and it are in the 30 positions illustrated in Fig. 1, the variable winding portion 2 is so connected with respect to the fixed winding portion i that the voltage applied between the secondary circuit conductors 3'.5 exceeds the primary circuit. voltage applied from conductors 3 and 4 to the winding portion l by the number of tapped parts of the winding portion 2 included in the circuit, which increases as the contact M moved progressively from engagement'with the contact 7 to engagement 40 with the contact I3, in which position the maximum secondary voltage is provided.

When it is desired to supply a voltage to the secondary circuit conductors 3--5 that is less than the'voltage supplied from the primary circuit conductors 3-4 to the unregulated winding portion I, the switch members l5 and 18 are moved to the positions shown in Fig. 2, in which positions the winding portions 1 and 2 are connected in series in reverse voltage relation, so that as the contact l4 progresses from engagement with the contact I along the row of tap contacts I to l3, the voltage applied to the secondary circuit is progressively decreased.

- While the arrangement shown in Figs. 1 and 2 66 provides a number or voltage regulating steps in excess of the number. of tap connections provided, by employing the same tap contacts both to decrease and to increase the secondary voltage with respect to the primary circuit voltage, and

thus to secure a mechanical advantage, it also introduces an undesirable characteristic into the transformer when the winding portions I and 2 are connected in voltage opposition, as in Fig. 2,

in that if a short circuit occurs on the secondary winding circuit, the reactance of the winding.

which normally reduces the short circuit current is greatly reduced in effectiveness.

vIn the circuit arrangement shown in Figs. 3 and 4, this disadvantage is avoided by providing a circuit connection from an intermediate-point 23 on the unregulated winding I through conductor 24, switch contact members 25 and 26 to the upper end of the unregulated winding portion- 2, so that in theposition oi the switch contact member 26 shown in Fig. 3, thatportion only of the unregulated winding I between conductor 3 and the point 23 is included in series with parts of the regulated winding portion 2, that part of the unregulated winding indicated by the numeral 2I being excluded from the secondary winding circuit. It will be noted that in Figs. 3 and 4, the primary circuit conductors 3 and 4 are connected to opposite ends of the unregulated winding I.

In the arrangement shown in Figs. 3 and 4 the voltages in the two sections l and 2 are al-.

' ways in the same direction, the voltage steps to provide a secondary voltage below the primary voltage being obtained by moving the contact member I4 along the row of contacts 1 to I3 with the switch contact member 26 in the position illustrated in Fig. 3. In order to obtain secondary voltages higher than the primary circuit voltage, the'contact member 26 is moved into engagement withthe switch contact member 21 as shown in Fig. 4, so that the-secondary circuit includes the whole of the unregulated winding portion I together withas many of the steps of the regulated winding portion 2 as may be determined by the position or the contact I4.

When the contact member. is moved along the contact row to engagement with contact I3 with the switch 26 in the. position illustrated in Fig. 3, the secondary voltage then corresponds to the primary voltage and before the contact member 25 is" moved from engagement with the contact member 25 into engagement with the contact member ,21. or from the position illustrated in Fig. 3 to the position illustrated in Fig. 4, the contact I4 must first be moved from engagement with contact I3 into engagement with an auxiliary contact 28,-, so that movement of the contact 26 will notinterrupt the secondary winding circuit.v This necessitates arranging the contact members 1 to I3 and 28 in a circular position so that the contact I4 may move in sequencefrom engagement with contact I3 to contact 28v and themto contact 1. This arrangement of the contact row has the disadvantage that the apparatus is not as easily mounted within the transformer tank and mustbe controlled by more complicated mechanismthan when the fixed contact members. are arranged in a straight line along which the movable contact I4 may operate.

In order to avoid the above pointed'out limi- 'tations in the arrangement ofthe step selector switch construction and operating mechanism, and to provide a rectilinear contact path, while at the same time avoiding the necessity of recontact 44 in Fig. 6 is versing the direction of current in the regulated winding portion with respect to the. direction in contacts, one of which is connected directly through a changeover switch in one operative position .to the secondary winding circuit 5, and

the other of which is connected through the nu? regulated winding portion I and the changeover switch in a second operative position to the conductor 5.

This construction is illustrated in Figs. 5, 6 and 7 in which the primary circuit conductors 3 and 4 are connected directly across the entire regulated winding portion 2. The lower part of the winding portion 2 is provided with tap connections between spaced points along the 'winding and tap contacts 3|, 32, 33, 34 and 35 that are arranged to be engaged by movable tap selecting' contacts 31 and 38, the contact 36 being connected through conductor 39 and the winding I to a contact 40 of a changeover switch, and the selector contact 38 being connected by conductor 42 to a. contact 43 of the changeover switch. The changeover switch is also provided manently connected to the secondary conductor 5 and is adaptedto engage one or both ofthe contact members 40 and 43.

' In the position of the various switch members illustrated in- Fig. 5, the minimum secondary voltage is provided between conductors 3 and 5. This voltage'corresponds to that portion of the primary circuit voltage appearing across that portion of the regulated winding. 2 between the tap contact 3| and conductor tor contact 38 is moved progressively from engagement with tap contact 3| into engagement with the contacts 32, 33, 34 and 35 in sequence, the voltage applied to the secondary circuit is increased to correspond voltage. As the selector contact 38 moves from the position illustrated in Fig. 5'to the position illustrated in Fig. 6,'the selector contact 31 remains in its initial position'in engagement with the fixed contact 3|. The portion of ,the winding 2 connected between contact, 3I and contact 35 corresponds in unregulated winding portion I wound on the same transformer core, so that as the switch contact member 44 is moved from the position illustrated in Fig. 5 to bridge both contact mambers 40 and 43, as illustratedin-Fig. 6, the two winding portions that are temporarily connected :in parallel develop a substantially equal voltage.

two winding portions when the member 44 bridges contacts 40 and. 43. The position of the switch temporary position which exists onlyduring the t ansition from the operated position shown in Fig. 5 to the operated position shown in Fig. 7. With the switch contact member 44 in the position shown in Fig. '7, the secondary circuit voltage is increased progressively by.moving the selector contact 31 progressively along the tap contacts 32, 33, 34 and 35.

to the primary circuit number of turns to the 3. As the selecmay be actuated either under load or under noload. If it is desired thatthe tapselector contacts be not operated under load, load switches may be provided and the selector contacts 31 and 38 may be sub-divided into a pair of contacts each, the individual contacts of each pair being operated from engagement with one tap contact to the adjacent tap contact only under no load condition for that selector contact.

Such an arrangement is shown in Fig. 8, in which the selector contact members and 46 acting as a pair, perform an equivalent function to the selector contact 31 of Figs. 5, fi-and 7 and the selector contacts '41 and 48 acting as a pair perform a function corresponding to the selector contact 38 of Figs. 5, 6 and 7.

In the switch positions illustrated in Fig. 8,

which corresponds to-the switch positions illustrated in Fig. 7 the contact pair 45, 46 connect the winding portion I through contacts 48 and 44 of the changeover switch to the conductor 5 in parallel circuit relation to the part of the winding portion 2 connected through the contact pair 41, 48 and contacts 43 and to the conductor 5. In the illustrated positions of the load switch contacts 5| and 6| the circuit divides between the two selector contacts of each pair andthrough the pair of reactor windings 54 and 51 associated with contact 5|, and a pair of reactor windings 64 and 61 associated with the contact 6|. When it is desired to move a pair of contacts, for example, the contacts 45 and 46 in a direction to increase the secondary circuit voltage, the con-.

tact 44 of the changeover switch is first moved to the right, as viewed in the drawings, out of engagement with the contact. 43. The contact 5| is then moved upwardly to bridge contacts 52 and 53, thus interrupting the circuit through selector contact 46. The contact 46 is then moved into. engagement with the next tap contact 32. Thereafter, the switch member 6| is moved downwardly to bridge the contact members and 56, the contact member 5| engaging the contact member 55 before separating from the contact member 52, in which position the windings 54 and 51 act as a'preven'tive auto to prevent the short circuit of the transformer winding section between segments 3| and 32 while preventing interruption of the circuit through the switch contactmember 5i. With the switch member 5| in engagement with the contacts 55 and 56, the selector contact 45 is moved into engagement with the tap contact 32 and the contact member 5| brought back to its normal position bridging contacts 52 and 55. The normal position of the contact 5|. maintains while both the contacts 45 and 46 are in engagement with the-same tap contact. The windings 54 and 51 which may be differentially related windings on the same magnetic core, to'provide a low reactance circuit for current in the winding I while at the same time, a high reactance circuit to the circulating current between the selector contacts 45 and 46 when in engagement with adjacent tap contacts during the interval in which the contacts 52 and 55 are bridged'by contact 5|.

When it is desired to move the pair of contact members 41 and 48 step by step along the row of tap' contacts 3| to 35, this may be done in the same sequence as described above with respect to step selecting contact of each pair.

the contacts 45 and 46, the load switch. contact member 6| being provided to engage contact members 63 and 62 in its upper position to short circuit the winding 64 and interrupt the circuit through contact 48, and in its lowerposition to bridge contacts 65 and 66 to short circuit the winding 61 and interrupt .the circuit through contact 41. In its mid-position the contact 6| bridges the contacts 62 and 65 while the selector contacts 41 and 48 are in engagement'with the same tap selector contact.

In Fig. 9 another embodiment of the invention is illustrated in which theeven-numbered tap contacts are connected to one step selecting contact of each pairof contacts, and the uneven numbered tap contacts are connected to the other For example, the selector contacts 68 and 18 engage only the tap contacts v3|, 33 and 35 and the selector contacts 69 and 1| engage only the tap contacts 32, 34 and 36.

In the arrangement of the circuits shown in extreme left position as shown in the drawings,

the middle position being only a transitory position while moving between the one or the other of the two operative positions.

In Figs. 10, 11 and 12, an arrangement is provided'in which the unregulated winding portion is subdivided into two halves and 8|. switching position shown in Fig. 10, the load circuit conductor 5 is connected through the unregulated winding portion 8| to the step selector contact 83, the step selector contact 84 being without current during its changeover position from engagement with tap contact 3| to engagement with contact 32, while the load switch contact member 93 is separated from contact 95 and in engagement with contact 94. In any tap position both selector contact members 83 and 84 are located on the same tap contact member, such as 32, so that the load current divides itself equally through the two tap contact members 83 and 84, and the two winding portions 80 In they and 8|. When the secondary circuit is completed through contacts 83 and 84, the changeover switch contact members 81 and 88 arein the positions illustrated in Fig, 10 in engagement with the contact members 90 and 92, respectively, and

' row. the switch member 93 will be rotated in a clockwise direction from its central position, as shown in Fig. 11, in whichcentral position it bridges the contact members and 94. When the contact member 93 is moved from engagement with thecontact member 95 to interrupt the circuit through the selector contact 91, the selector contact 91 is then moved downwardly to the next tap contact position. After the contact 93 has moved sufliciently to again engage the contact 95 and while out of engagement with the contacts 94 or 99, the selector contact .96 is moved downwardly into engagement with the next lower tap contact member of the row, and the contact s: is again moved to the pontion shown in Ids. 11 to bridge t e contacts 85 and 94, thus dividin the load current equally between the selector contacts at am" 31.

During-movement of the selector contact members 9S and 91 along the tap contact row, the

over switches 31 and 33 are simultaneously moved l from the positions shown in Fig. 12 through the positions shown in Fig. 11 to the positions shown in Fig. 10. During the transitory or temporary position of the switch contact members 31 and as shown in rig-11, the unregulated windings 80. and II are connected in parallel with that portion of the regulated winding 2 between the tap contact 3| and the tap contact 35. After the changeover contacts 31 and 3! are in the positions illustrated in Fig. ,10, further increase of the secondary voltage is ei'iectedby rotating the contact member first to the position shown .in Fig. 10, out'of engagement with the contact member 95, in which podtion the selector contact member 84 is moved i.'rom engagement with the tap contact .3l to the next lower tap contact 32,

while 'thecircuit-throush'the tap contact 34 and the winding 3' is interrupted. As the load switch contact as continues to move in a clockwise direction, it temporarily engages the contact members SI and 99 to include the winding portions II! and I02 in the local circuit between tap contacts 3| and 32 until the switch contact member .3 has moved suillciently to interrupt the circuit through the selector contact l3,- the winding portion circuit is interrupted, the selector contact as is moved downwardly into engagement with the next tap contact member, such as 32. and. the load switch contact member I is brought to its central position, bridging II and !l to complete the tap change.

Successive tap changes, during each step oi! which the selector contacts 03 and 3| are moved downwardly one tap contact position, are 'eflected in the same manner, theload switch contact it making a complete revohition during each complete tapchange. 1

Whenthetapchangin8-mechanismisoperated inareversedirectiontodecrcuethevoltagesuppliedtothesecondaryorloadcircuitconductors 3'-I, the load switch contactiI-is revolved in a counter-clockwise direcflon as viewed in the drawings; one complete revolution during each complete tap changing step, and the selector contact members 33 and 3 are moved upwardly in the reverse order above described, each selector contact being moved from engagement with one tap contact to the next tap contact while the circuit through the load switch is interrupted.

, A resistor I is provided connected between in-- terme'diate points. III, and lit on the winding portions I and 3| to prevent the voltages applied to either winding to float to undesirable values while the circuits therethrough are interrupted during tap changing "operations.

Obviously, the upper portions 1 be omitted, depending upon the .voltages of the I and the contacts 34 and ll. While this of the regulatedwindings 2 between the tap contact 31' and the conductor 3 shown in Figs. 5 to 12 inclusive, may

.for effecting the sequential operation of the various switch elements in the order described are provided employing any convenient arrangement of cams, shafts, changeover cables, according to known mechanisms for efiecting desired sequential operation of switch contact elements.

two movable selector contacts cooperating with the tap contacts, each selector contact being movable over a range corresponding to the number of tap contacts without movement of the other selector contact, and a changeover switch having two operative positions for connecting a selected one of ,said selector contacts to said load'circuit conductor, said unregulated winding portion being.

included in circuit between one of said selector contacts and said changeover switch.

2. In a regulating transformer, in combination, i

a regulated winding portion provided with a plurality of tap connections at spaced intervals therealong and an unregulated winding portion,

a tap changing switch mechanism including tap contacts connected to the several tap connections, two pairs of selector contacts, cooperating with the tap contacts, a pair of intermediate circuit conductors and a pair of load circuit conductors, a load switch associated with each pair of selector contacts for selectively connecting the one or the other of each selector contact of a pair to an intermediate circuit conductor, and -a changeover 'switch having two operative positions for connecting a selected one of said intermediate circuit conductors to one load circuit conductor, said unregulated winding portion being included in circuit with one of said intermediate circuit conduetors between a selector switch of one pair and said changeover switch to serve as a part of the useful output voltage source.

v 3. In a regulating transformer, in combination, a regulated winding portion provided with a plurality of tap connections at spaced intervals therealong and an unregulated winding portion, a pair of intermediate circuit conductors and a pair of load circuit conductors, a tap changing mechanism including tap contacts connected to'the several taps, two pairs of selector contacts, cooperating with the tap contacts, a load switch associated with each pair of selector contacts for selectively connecting the one or the other of each selector contact of a pair to one of said intermediate circuit conductors, and a changeover switch having two operative positions for connecting a selected one of said intermediate circuit conductors to one of said load circuit conductors, said unregulated winding portion being included in circuit between one of said intermediate circuit conductors and said changeover switch to serve as apart of the useful output voltage source, each of said pairs of selector contacts being movable over the whole regulating range of said the other-pair.

4.'In a regulating transformer, in combination, a regulated winding portion provided with a plutap contacts without movement of rality of tap connections at spaced intervals therealong and an unregulated winding portion, a pair of intermediate circuit conductors and a pair of load circuit conductors, a tap changing switch mechanism including tap contacts connected to the several tap connections, two pairs of selector, contacts cooperating with the tap contacts, a load switch associated with each pair of selector contacts for selectively connecting the one or" the other'of each selector contact of a pair to an intermediate circuit conductor, each pair of selector contacts being movable over a range corresponding to the number of tap contacts without movement of the other pair of selector contacts, and a changeover switch having two operative positions for connecting a selected one of said intermediate circuit conductors to one of said load circuit conductors, said unregulated winding portion being included in circuit between one of said intermediate circuit conductors; and said changeover switch, means for coordinating the operationof said selector contacts-and of said load switches so that a selector contact is moved from engagement with one tap contact to the next tap contact only when the circuit therethrough is interrupted by the associated load switch.

5. In a regulating transformer, in combination, a pair of load circuit conductors, a regulated winding portion having a tapped part provided with a plurality of tap connections at spaced intervals therealong and an unregulated winding portion, and a tap changing switch mechanism including tap contacts connected to the several tap connections, two movable selector contacts arranged for successive operative engagementwith each of said tap contacts, each selector contact being movable independently of the movement of the other, and a changeover switch connected to one of said load circuit conductors and having two operative positions for connecting a selected one said selector contacts are in engagement with tap selector. contacts at opposite ends of said tapped'winding part. 6. In a regulating transformer, in combination, a pair of load circuit conductors, a regulated winding portion having a tapped part provided with a plurality of tap connections at spaced intervals therealong and an unregulated winding portion having a number of turns corresponding to the number of turns of the tapped part of the regulated winding portion, and a tap changing switch mechanism including tap contacts connected to the several tap connections, two movable selector contacts arranged for successive operative engagement with each of said tap contacts, each selector contact being movable independently of the movement of the other, and a changeover switch connected to one of said load circuit conductors and having two operative positions for connecting a selected one of said selector contacts to said load circuit conductor, said unregulated winding portion being connected in circuit between one of said selector contacts and said changeover switch,

and said changeover switch being arranged to transfer the connection of said load circuit conductor from the one to the other of said selector contacts while said selector contacts are in engagement with tap selector contacts at opposite ends of said tapped winding part.

MAX SCHWAIGER. 

